Subject: General Aptitude · Chapter: Time and Distance · Exam: · Marks: · Difficulty:
A can complete a journey in 10 hours. He travels first half of the journey at the rate of 21 km/hr and second half at the rate of 24 km/hr. Find the total journey in km.
(a)220 km
(b)224 km
(c)230 km
(d)234 km
Answer
Answer (as printed): B
Explanation
Let the total distance be $x \mathrm{km}$. Then, $$\begin{aligned} & \frac{\frac{1}{2} x}{21}+\frac{\frac{1}{2} x}{24}=10 \Rightarrow \frac{x}{21}+\frac{x}{24}=20 \\ \Rightarrow \quad & 15 x=168 \times 20 \Rightarrow x=\left(\frac{168 \times 20}{15}\right)=224 \mathrm{km} . \end{aligned}$$